Frequency-meter.



A. F. POOLE.

' FREQUENCY METER. APPLICATION FILED DEG. 16, 1907.

i" 036 900 Patented Au 27, 1912.

2 SHEETB-SHEET 1.

. v A InVenlTv WIITIEEEES ATfffurPPuuiE A. P. POOLE. FREQUENCY MET R; APPLICATION FILED DEO.16, 1907.

1,036,900, Patented Aug. 27, 1912.

2 SH EETS-SHEET 2.

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FREQUENCY-METER.

Specification of Letters Irateht. Patented Aug, 27, 1912,

Application filed December is, 1907. Serial no. 403,594. 7

To all whom it may concern Be it known that I, ARTHUR citizen of the United States, residing at Wheeling, in the county of Ohio and State of West Virginia, have invented a certain new and useful Improvement in Frequency- Meters, of which the following is a full, clear, concise, and exact description, reference being had to the accompanying drawings, forming a part of this specification.

The invention herein described and claimed is intended for measuring the frequency of alternating or pulsating currents of electricity.

There are in use at the present time certain devices for measuring the frequency of such -currents at a distance from the central station. One of the best frequency meters of this type is that in which there is a plurality of tuned reeds, each :reed having a natural rateof vibrationdifi'ering from that of other reeds of the set. An electromagnet may be connected with the circuit whose frequency is to be measured, and this electromagnet acts upon the reeds to cause their vibration. Then the periodicity of the current to be measured corresponds with the natural rate of vibration of any reed of the set, that particular reed will be set in vibration. The natural rate of the reed being known, the frequency of the current to be measured is thus ascertained. When the frequency to be measured falls midway be- F. POOLE, a

tween that of two reeds, both reeds will be set in vibration, but through a smaller amplitude than in the case in which the frequency of the current corresponds exactly with that of one of the reeds. When two reeds are thus setin vibration, the observer knows that the frequency of the current which is being measured is somewhere between that of the natural rates of vibration of the two reeds. meter is not absolutely accurate in its measurements, and the determination of the frequency of a current which is being measured involves to a considerable extent the personal equat on of the man who is reading the instrument. Furthermore, this vibrating reed meter'requires very considerexpensive. A y I y g My invention prov'des a far cheaper fre- Such a frequency in its manufacture, and is quite iii-ch is more acciz rate inthe determination ofthe precise frequency of the current in question.

The preferred form of my invention has been designed especially for use in determining the freqiiency of alternating ringing currents ,used in the operation of harmonic and. multi-frequency party line telephone systems of the selective type. Itis, however. useful for other purposes, and may be its escapenient, the clock train driying suit able hands or pointers by which the degree of rotation or movement of the clock mechanism may be read g'nnd in conjunction with this an electromagnetic mechanism controlling the escapement. the energizing coils of theelectromagnet being connected with the circuit in which the frequency is to be measured. The vibration of the armature of the elect-romag'net thus connected in circuitis determined by the frequency of the currientin a circuit to be measured. The armature in turn controls the escapement and the escapement the clock train, so that the rotation of the clock hands may he used as an index ofthe number of reversals in thealternating current. Bynsing a stop watch and timing the movement of theh'ands upon their dial, a very accurate determination of the frequency in question may be made. My inventioh and its method of se, will be more clearly understood by reference to the accompanying drawings, in which Figure 1 is a front View of the frequency meter of my invent-ion, parts of the dial be-' ing broken awayin order to more clearly illustratethe inner construction; Fig. 2 is a side elevation, Fig. 3 is an enlargedview of the armature and escapement mechanism. showing the pallet-s in. one position, and Fig. 4 is a similarly enlarged View of the escanement showing the pallets in their alternative position.

Referring to these drawings, it will be seen that I have mounted upon a suitable base plate 11. the electromagnetic mechanine-10f a telephone ringer. This acne comp a essentially the U-shaped electro mag in, whose poles appear at 1'3 and At. the lower part town the escapement s pivoted pallets 26 anown anchor escape lever 28 .is mounted shaft which carries the 'l'i'. liliittending from the to a, position between in'ked lever 28 is the 0011-.

re ad; train the mainspring, 1, tends to to i. in the direc- 31. When the 'escapemcnt i shown in Fig.3,the tooth are upon the pallet 26 tendaft in the direction of the l is e left hand tine of the forked t a, pressure upon the com r 30 in the direction of the ar- Tit-l normal conditions, howi. cssurc is not quite sutlicient to so tl armature to which the'lever 30 is .hed to swing into its alternative position, l'iccanse the polarization which is efrted by the permanent magnet 15 causes a sl t magnetic attraction tending to hold. the armature in that one of'its alternative positions in which it happens. at the time to be. When the escapement takes the osition shown in Fig. 4, the tooth will exert a pressure against the pallet 27 tending to rot the rocl: shaft in the direction of the arrow Elli. This will cause the forked lever 28 to exert a pressure upon thelever 30 in' the dire on of the arrow 37; as in the previous c however, the slight pressure carried by the escapemcntmechanism is not quite suilicioni' to throw the armature into the alternative position against the attraclion due to the polarization of, the clec' troniagnet and arnmtnre. When, however, K current impulse is caused to flow in the ni amt 232. the p'olarizaticl due to rinanent magnet will be decreased to an extent that the escapement will the armature into its reverse position.

also reversed, the polarivibrate at a rate correspondin frequency of the current in t e magnet pressure upon the pallet,

" direction through the wind'ag of the current through the electro will be understood that when an alternating current flows through the electromagnet WlIlCllIlg, the armature will. be caused to with the windings. One tooth of the escapement wheel will therefore be passed for each cycle of the alternating current. v The clock hands record the rotation of the escapement wheel, and, the gear ratios being properl pro-determined, the movement of the ban 9 may be read direct ascycles of alternating current. I prefer to use a dial marked in the manner shown in the drawing, because this enables me to use the ordinary clock trains, which can bepurchased very cheaply measurement of alternating currents of relatively small power thatthe mainspring of the clock train actlngthrough the escape-' ment aids the current in causing the vibration ofthe armature. This will be'apparent to those skilled in the art, when it isborne in mind that the frequency of alternating currents is sometimes extremely high and that under ordinary circumstances the armature of an electromagnet must have very slight inertia if it is to follow the reversals of a high frequency alternating current. The connection which exists between the mainspring of the clock train of the meter of my invention and the vibrating armature ofvt he bell magnet is such as to produce the effect of a very light armature. This, of course, is due to the fact, as previously explained, that the cscapemcnt acts always with a tendency to swing the pallets and the vibrating mechanism associated therewith into their reversed position. The spring pressure, therefore, overcomes to a large extent the inertia which would otherwise be present in the somewhat heavy armature and lever mechanism, thus permitting the armature to vibrate strictly in accordance with the cyclic reversals of alternating currents of very high as well as of very low frequencies. Actual tests have shown that this instrument is capable of laccurately'recording such reversals at all While I have herein'shown and described thepreferred emhodimcnt of my invention, it will be apparcnt'to those skilled in the art that many i'nodi io'ations and changes may Y member and be made Withona departing from the spizit thereof; conseqnenely i do not is in of my invention in the accompanying claims.

I claim as my invention:

1. In a frequency meter, a she'l -t, p secured upon said sliaii, a dial (W said, pointer moves a toothed wheel tively connectid with said slmit an oscilln ing pallet member cooperating wi toothed Wheel an OXiQHSiOEl rigid w pellet membei' and ii n'ving a slot, pol

eleei ome 'nc an oscillating armature A 2: a .J I a ct a part QXiQ in.

armature mile l'lie slot in sale e 1 causing Hie movement of said pail I mom and the engageincnlbetween said pnl member and said toothed Wlicei being such that the operation the former iends drive the lattei' and a spring associnl'ed with said shaft and tending to drive it in iii direciion in which the operation of die nllet tends [0 drive it the shaft being; operated by the eonioinec effoi'ls l oi sand spring and said elec'liomasgne'li when ins lai ter is energized.

2. In a fleqnency meter, 22 she??? a poini'er secured upon said shaft, a dial over which said pointer n'xovcs, a toothed wheel open atively connected with said Sllfifi, an

leting pallet member coiiserniing' with Wheel, e polarized l ictl'Omfigileli'Wliil :1 U- shaped core, an oseilieting armature for sei elecbromagnet pivoted midway between two lime ai the open end of core, means for opemtively connsc armature with said pallet menib spring associated Willi shaft ing to drive ii, the relation of a said toothed wlieei that the latte: wiil ive lidvanced each enei'gisation of th elect i 3. In a frequency met-e? e s.

coice armature said "p011 said shaft a dial over which A er moves, a toothed Wheel ope?- with said she-ft, an oscilpzillet member co-r'ipeiating with said polarized eleciiomagnet with a U- ore, an oscillating armature for said U'OIT pivoted midway between the lines at the open end of said U-slisped erm extending rigidly fZOEG'SfllCi said :srm arranged to enpallet member, and a spring" as and tending to drive pellet ineznloer such that the latendsixap for each enerd poim'cr indevelociiy ratio s, n iool'iied Wheel OPQI- Jnieeted with said shaft, an oscil- :nenioei' cooperating with (he 'iwei, e poiarized clectroinegnei; shaped core an oscillating armeid electioznagnct pivoted midway e two limbs said core so-as to to respond in high mics of :6-

al v electionmgnet being l3 connected with said 1* audits kinetic energy being these directly associated pzn'is,

a spring associated with said shaft and ing to drive it, said first-named pointer 'ieing' advanced one step for each energizeef ills elecci'ornzignei.

WliHGSS whereof, lierennio subscribe 7 name @1115 i253. day December, A. 1).,

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